Information on update: Warning likelihood increased, due to greater focus across the east of the warning area. Start time brought forward to cater for possible heavy morning showers across southeastern areas. After early rainfall in the southeast of England, showers and thunderstorms are likely to develop more widely across the warning area during the afternoon. The focus of torrential downpours will probably be across the eastern half of the warning area and perhaps also across some southern coastal counties further west. Hail and gusty winds may prove additional hazards. Some areas, particularly in the west, may largely avoid the heavier showers.
Rainfall amounts will vary considerably from place to place, but hourly totals could approach 30 mm in some places, with a few locations perhaps picking up 60 to 80 mm from successive showers and storms through the day. For further details see https://www.metoffice.gov.uk/weather/warnings-and-advice/uk-warnings